Energy storage power station power control distribution method and system based on station level networking control

Abstract

The invention provides an energy storage power station power control distribution method and system based on station level networking control. The method comprises the specific steps that S1, a station level networking control structure is constructed, the control structure is divided into an upper layer and a lower layer, the upper layer is a station control center, and the lower layer is an energy storage station; s2, the station control center generates a total power reference instruction of a station PCC point by simulating a synchronous machine power angle swing equation; and S3, according to the operation state of the lower-layer energy storage station, the operation state of the energy storage station is judged, if the state is normal, a total power reference instruction is received, and power reference is distributed to each energy storage power station according to the energy storage level, otherwise, the energy storage station quits operation, and a charging and discharging program of the energy storage station is started. According to the invention, the station control center outputs the total power reference of the station, thereby guaranteeing the accurate control of the total power of the station. And distributing power according to the actual capacity of each energy storage power station, so that the actual output of each energy storage is matched with the energy storage level.

Description

Technical Field

[0001] The present invention relates to the technical field of energy storage power stations, and in particular to a power control distribution method for an energy storage power station based on site-level networking control, and a power control distribution system for an energy storage power station based on site-level networking control. Background Art

[0002] With the vigorous development of new energy grid-connected control technology, the penetration rate of renewable energy in new power systems continues to increase. Due to the intermittent and volatile characteristics of new energy, energy storage power stations, as a key technology that can balance the fluctuations in power supply and demand, have the characteristics of flexible charging and discharging and rapid response, and have been widely used in new power systems. At present, energy storage power stations are mostly connected to the grid in the form of stations through grid-following (GFL) converters and connected to the grid at the point of common coupling (PCC) of the station. However, the traditional grid-following converter tracks the grid phase through the phase-locked loop (Phase-Locked Loop), and cannot actively provide frequency and voltage support in the event of a fault, which affects the safe and stable operation of power systems with high new energy penetration. Therefore, the grid-forming (GFM) converter has been widely valued and developed because of its ability to simulate the characteristics of synchronous machines and actively improve the frequency and voltage support for the system. At present, many new energy stations in my country have begun to implement grid-forming transformation of stations.

[0003] However, there are still many problems in transforming energy storage power stations into grid-based ones. First, with the increase in the penetration rate of new energy, centralized energy storage stations will be equipped with thousands of energy storage power station units in the future. If all of them are transformed into grid-based ones, the additional engineering costs will not be negligible. Secondly, the grid-based converter simulates the synchronous machine swing equation to spontaneously respond to power, which cannot make the power generated by each energy storage power station match its actual energy storage level, and it is difficult to achieve precise control of the total power of the station; finally, the grid-based converter is essentially connected to the grid in the form of a voltage source. Compared with the grid-based converter that is connected to the grid in the form of a current source, it will bring more serious stability problems when multiple machines are connected in parallel, such as power coupling oscillation problems.

[0004] Therefore, there is still a lack of further research at home and abroad on how to ensure the economy, control accuracy, safety and stability while carrying out grid-based transformation of station-level energy storage power station systems. Summary of the invention

[0005] The present invention provides a power control distribution method and system for an energy storage power station based on site-level networking control, which is used to solve the defects in the prior art of ensuring the economy, control accuracy, safety and stability of the site-level energy storage power station system while performing networking transformation.

[0006] On the one hand, the present invention provides a power control and distribution method for an energy storage power station based on site-level network control, characterized in that it includes:

[0007] S1: Construct a station-level network control structure. The control structure is divided into two layers, the upper layer is the station control center, and the lower layer is the energy storage station.

[0008] S2: The station control center generates the total power reference command of the station PCC point by simulating the synchronous machine power angle swing equation.

[0009] S3: According to the operating status of the lower-level energy storage station, the operating status of the energy storage station is judged. If the status is normal, the total power reference instruction is received, and the power reference is allocated to each energy storage power station according to the energy storage level. Otherwise, the energy storage station exits operation and starts the charging and discharging program of the energy storage station.

[0010] According to a power control and allocation method for an energy storage power station based on site-level network control provided by the present invention, in step S2, a method for generating a total power reference instruction includes:

[0011] S21: The PCC point aggregate power is input to the station control center, and the PCC point voltage phase angle is provided by simulating the rotor motion equation to generate the control equation.

[0012] S22: Based on the voltage phase angle, the voltage vector is converted to a virtual synchronous d q Coordinate system.

[0013] S23: Based on d q The steady-state circuit equation in the coordinate system is based on the virtual internal potential E on the d-axis v The difference between the voltage at the grid-side converter terminal in the virtual synchronous coordinate system and the voltage at the grid-side converter terminal in the virtual synchronous coordinate system, divided by the set virtual impedance X eq , and obtain the output current reference value of the station.

[0014] S24: Use the instantaneous power equation to convert the current reference value into a total power reference command.

[0015] According to a power control and distribution method for energy storage power stations based on site-level network control provided by the present invention, in step S21, the formula of the control equation is expressed as follows:

[0016]

[0017] Where P ref，total is the total active power reference of the station, P sum is the total active power collected by the station at the grid connection point, ω p ,θ pare the speed and phase angle of the virtual synchronous coordinate system, ω0 is the rated speed, J and D are the virtual moment of inertia and damping, ω is the speed, and t is the rotation time.

[0018] According to a power control and allocation method for energy storage power stations based on site-level network control provided by the present invention, in step S23, the virtual internal potential E v The control equation is:

[0019]

[0020] Among them, K v is the voltage droop control coefficient, E0 and U pref are the virtual internal potential and terminal voltage amplitude reference values, U p is the terminal voltage amplitude, T r is the voltage detection delay, and s is the differential operator.

[0021] According to a power control and allocation method for energy storage power stations based on station-level network control provided by the present invention, in step S24, the calculation equation of the total power reference instruction is expressed as:

[0022]

[0023] Where P ref，pcc and Q ref，pcc are the power reference instructions of the PCC point of the station, is the voltage component of the station PCC point under the d-axis, It is the output current reference value of the station under the d-axis.

[0024] According to a power control and allocation method for energy storage power stations based on site-level network control provided by the present invention, in step S3, SOC i is the current energy storage level of the i-th energy storage power station. The steps of judging the operating status of the energy storage station include:

[0025] S31: According to the current energy storage level, the working state of the energy storage station is divided into three ranges, namely emergency discharge mode, normal operation mode, and emergency charging mode. SOC is defined max and SOC min It is the upper and lower limits of the energy storage power station operating in normal operation mode.

[0026] S32: When SOC min <SOC i <SOC max When SOC is , the energy storage power station can operate normally, receive the total power reference instruction, and allocate power reference to the energy storage power station according to the energy storage level. i >SOC max or SOCi <SOC min When the energy storage power station is shut down, the energy storage power station will be shut down and the charging and discharging procedures will be started.

[0027] According to a power control and distribution method for energy storage power stations based on station-level network control provided by the present invention, in step S32, a method for allocating power references to each energy storage power station includes: uploading the energy storage level data of each unit to the station control center at a preset time period, synchronously updating the power distribution ratio coefficient of the energy storage power station, and then allocating the total power reference instruction to each unit.

[0028] According to a power control allocation method for energy storage power stations based on station-level network control provided by the present invention, in step S32, the specific allocation method of allocating the total power reference instruction to each unit is expressed as follows:

[0029] P ref,i =k i P ref,pcc

[0030] Q ref,i =k i Q ref,pcc

[0031]

[0032] Where P ref,i , Q ref,i is the total power reference command allocated to each unit, k i is the power allocation ratio coefficient of the i-th energy storage power station, and n is the total number of energy storage power stations operating within the normal range.

[0033] According to a power control and distribution method of an energy storage power station based on station-level networking control provided by the present invention, in step S1, the energy storage station is controlled by a grid-following control method, and the grid-following control method is to make the power output track the total power reference instruction through power-current dual-loop control, and cooperate with the phase-locked loop to maintain phase synchronization with the PCC point.

[0034] On the other hand, the present invention also provides a power control and distribution system for an energy storage power station based on a station-level network control, which adopts a power control and distribution method for an energy storage power station based on a station-level network control as claimed in any one of claims 1 to 9, and the distribution system comprises:

[0035] Virtual synchronization module: The station control center inputs the PCC point aggregate power, provides the PCC point voltage phase angle by simulating the rotor motion equation, and generates the control equation.

[0036] Coordinate transformation module: Based on the voltage phase angle, the voltage vector is transformed into a virtual synchronous d q Coordinate system.

[0037] Current reference module: based on d q The steady-state circuit equation under the axis is based on the virtual internal potential E on the d axis. v The difference between the voltage at the grid-side converter terminal in the virtual synchronous coordinate system and the voltage at the grid-side converter terminal in the virtual synchronous coordinate system, divided by the set virtual impedance X eq , and obtain the output current reference value of the station.

[0038] Power reference calculation module: Uses the instantaneous power equation to convert the current reference value into a total power reference command.

[0039] Decision module: judge whether the operation status of the energy storage station is normal, if it is, the energy storage station receives the total power reference instruction. Otherwise, exit the operation mode and start the charging and discharging program of the energy storage station.

[0040] Power reference allocation module: The energy storage level data of each unit is uploaded to the station control center at a preset time period, the power allocation ratio coefficient of the energy storage power station is updated synchronously, and then the total power reference instruction is allocated to each unit.

[0041] The present invention provides a power control and distribution method and system for energy storage power stations based on station-level network control, which ensures accurate control of the total power of the station by outputting the total power reference of the station through the station control center. Power is distributed according to the actual capacity of each energy storage power station so that the actual output of each energy storage matches its energy storage level. The lower-level units retain their grid-type multi-machine parallel control structure, and there is no need to carry out network transformation on the actual units, which ensures the economy of the transformation and the safety and stability of the control. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0043] Figure 1 It is a flow chart of a power control and allocation method of an energy storage power station based on site-level network control provided by an embodiment of the present invention;

[0044] Figure 2a A station structure of a power control and distribution method for an energy storage power station based on station-level networking control provided by an embodiment of the present invention;

[0045] Figure 2b A site control center of a power storage power station power control and distribution method based on site-level networking control provided by an embodiment of the present invention;

[0046] Figure 2c It is a unit control of a power control and distribution method of an energy storage power station based on a site-level network control provided by an embodiment of the present invention;

[0047] Figure 3 It is the delineation of the normal operating range of the energy storage device provided by the embodiment of the present invention;

[0048] Figure 4a The four-machine grid-connected energy storage power station system P provided by the embodiment of the present invention ref Simulation results of the power change at the PCC point during mutation;

[0049] Figure 4b It is a simulation result of the power change at the PCC point when the grid voltage phase suddenly changes in the four-machine grid-connected energy storage power station system provided by an embodiment of the present invention;

[0050] Figure 4c It is a simulation result of the voltage change at the PCC point when the grid voltage amplitude suddenly changes in the four-machine grid-connected energy storage power station system provided by the embodiment of the present invention;

[0051] Figure 4d It is a simulation result of the change in output power of each unit when the unit allocation coefficient in the station of the four-machine grid-connected energy storage power station system provided by the embodiment of the present invention changes. DETAILED DESCRIPTION

[0052] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the drawings of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0053] Combine the following Figure 1 - Figure 4 describes a power control and distribution method and system for an energy storage power station based on site-level network control according to the present invention.

[0054] Figure 1 It is a flow chart of a power control and distribution method of an energy storage power station based on site-level network control provided by an embodiment of the present invention.

[0055] like Figure 1 As shown, an embodiment of the present invention provides a method for controlling and allocating power of an energy storage power station based on site-level network control, and the method mainly includes the following steps:

[0056] S1: Construct a station-level network control structure. The control structure is divided into two layers, the upper layer is the station control center, and the lower layer is the energy storage station.

[0057] The steps for the lower-level energy storage station to adopt a grid-following control method include using traditional power-current dual-loop control to make the power output track the total power reference instruction, and cooperating with the phase-locked loop to maintain phase synchronization with the PCC point.

[0058] S2: The station control center generates the total power reference command of the station PCC point by simulating the synchronous machine power angle swing equation.

[0059] The steps for the station control center to generate the total power reference command of the station PCC point by simulating the synchronous machine power angle swing equation are as follows:

[0060] S21: Virtual synchronization link: The PCC point aggregates power input to the station control center, provides a PCC point voltage phase reference by simulating the rotor motion equation, and generates the control equation.

[0061] In step S21, the control equation is expressed as:

[0062]

[0063] Where: P ref，total is the total active power reference of the station, P sum It is the total active power collected by the station at the grid connection point. p ,θ p are the speed and phase angle of the virtual synchronous coordinate system. ω0 is the rated speed, and its value is 100πrad / s. J and D are the virtual moment of inertia and damping, respectively. ω is the speed, and t is the rotation time.

[0064] S22: Coordinate transformation link: In the coordinate transformation link, the voltage vector is transformed into the virtual synchronization d based on the phase angle output by the virtual synchronization link. q Coordinate system.

[0065] S23: Current reference calculation link: based on d q The steady-state circuit equation under the axis is based on the virtual internal potential E on the d-axis of the virtual synchronous coordinate system. v The difference between the voltage at the grid-side converter terminal in the virtual synchronous coordinate system and the voltage at the grid-side converter terminal in the virtual synchronous coordinate system is divided by the set virtual impedance X eq , the output current reference value of the station in the virtual synchronous coordinate system is obtained, and its expression is:

[0066]

[0067] In the formula, the superscript “p” represents the component of the vector in the virtual synchronous coordinate system. dref p 、i qref p are the reference values ​​of the station output current under the d and q axes, u pdp 、u pq p It is the component of the voltage at the PCC point of the station under the d and q axes.

[0068] In step S23, the virtual internal potential E v The governing equation is: The virtual internal potential E v The value of is obtained by simulating the automatic voltage control link (Automatic Voltage Regulator, AVR) of the synchronous machine, which is in a droop relationship with the terminal voltage, and its control equation is:

[0069]

[0070] Among them, K v is the voltage droop control coefficient, E0 and U pref are the virtual internal potential and terminal voltage amplitude reference values, U p is the terminal voltage amplitude, T r is the voltage detection delay, and s is the differential operator.

[0071] S24: Total power reference calculation link: Use the instantaneous power equation to convert the current reference value into a total power reference instruction. The calculation equation is:

[0072]

[0073] Where P ref，pcc and Q ref，pcc They are the power reference instructions of the PCC point in the station and the total power reference instructions of all units in the station.

[0074] S3: According to the operating status of the lower-level energy storage station, the operating status of the energy storage station is judged. If the status is normal, the total power reference instruction is received, and the power reference is allocated to each energy storage station according to the energy storage level. Otherwise, the operation is exited and the charging and discharging program of the energy storage equipment is started.

[0075] In step S3, define SOC i is the current energy storage level of the i-th energy storage power station. The steps of judging the operating status of the energy storage station include:

[0076] S31: Divide the working state of the energy storage station into three ranges according to the current energy storage level, such as Figure 3 As shown: emergency discharge mode, normal operation mode, emergency charging mode, define SOC max and SOC min It is the upper and lower limits of the energy storage power station operating in normal operation mode.

[0077] S32: When SOC min <SOCi <SOC max When SOC is , the energy storage power station can operate normally, receive the total power reference instruction, and allocate power reference to the energy storage power station according to the energy storage level. i >SOC max or SOC i <SOC min When the energy storage power station is shut down, the energy storage power station will be shut down and the charging and discharging procedures will be started.

[0078] In step S32, the method for allocating a power reference to each energy storage power station includes: uploading the energy storage level data of each unit to the station control center at a preset time period, synchronously updating the power allocation ratio coefficient of the energy storage power station, and then allocating the total power reference instruction to each unit. Since the current reference calculation link calculates the PCC point collection current required for the station to maintain its VSG characteristics, the power obtained by the following formula is the total power output required for the station to maintain the VSG characteristics. Regardless of the control structure of the single machine in the field, as long as the total power generated by the station is equal to the power reference obtained by the formula, the station as a whole can show VSG characteristics to the outside.

[0079] In step S32, the specific allocation method of allocating the obtained total power reference command to each unit is:

[0080] P ref,i =k i P ref,pcc

[0081] Q ref,i =k i Q ref,pcc

[0082]

[0083] Where P ref,i , Q ref,i is the total power reference command allocated to each unit, k i is the power allocation ratio coefficient of the i-th energy storage power station, and n is the total number of energy storage power stations operating within the normal range.

[0084] The energy storage power station power control allocation method based on station-level network control provided in this embodiment ensures accurate control of the total power of the station by outputting the total power reference of the station through the station control center. Power is allocated according to the actual capacity of each energy storage power station so that the actual output of each energy storage matches its energy storage level. The lower-level units retain their grid-type multi-machine parallel control structure, and there is no need to carry out network transformation on the actual units, which ensures the economy of the transformation and the safety and stability of the control.

[0085] Based on the same general inventive concept, the present invention also protects a power control and distribution system of an energy storage power station based on a station-level network control, which can be controlled by using the above-mentioned power control and distribution method of an energy storage power station based on a station-level network control. The power control and distribution system of the energy storage power station includes:

[0086] Virtual synchronization module: Input the PCC point aggregate power to the station control center, provide the PCC point voltage phase angle by simulating the rotor motion equation, and generate the control equation.

[0087] Coordinate transformation module: Based on the voltage phase angle, the voltage vector is transformed into a virtual synchronous d q Coordinate system.

[0088] Current reference module: based on d q The steady-state circuit equation under the axis is based on the virtual internal potential E on the d axis. v The difference between the voltage at the grid-side converter terminal in the virtual synchronous coordinate system and the voltage at the grid-side converter terminal in the virtual synchronous coordinate system is divided by the set virtual impedance X eq , and obtain the output current reference value of the station.

[0089] Power reference calculation module: Uses the instantaneous power equation to convert the current reference value into a total power reference command.

[0090] Decision module: judge whether the operation status of the energy storage station is normal, if it is, the energy storage station receives the total power reference instruction. Otherwise, exit the operation mode and start the charging and discharging program of the energy storage station.

[0091] Power reference allocation module: The energy storage level data of each unit is uploaded to the station control center at a preset time period, the power allocation ratio coefficient of the energy storage power station is updated synchronously, and then the total power reference instruction is allocated to each unit.

[0092] A four-machine grid-connected system of a grid-following energy storage power station is built in the DigSILENT\PowerFactory simulation software as an embodiment of the present invention. Its grid topology is shown in Figure 2(a) and the control parameters are shown in Table 1. Figure 1 , build a station-level network control structure, and the operation steps of the station control structure are shown in Figure 2(b). The power reference of the grid-following energy storage power station is distributed, as shown in Figure 2(c). In the figure: the superscript "si" represents the component of the dq coordinate system of the phase-locked loop of the i-th unit. P ref，i and Q ref，i are the active and reactive references assigned to the i-th unit respectively. dref ,i si 、i qref ,i si are the dq axis current reference of the i-th unit, U si , U tiis the high voltage side voltage and port voltage of the converter filter inductor, u sd i si 、u sq i si 、u td i si 、u tq i si Its dq axis component. i is the phase angle of the dq coordinate system of the phase-locked loop of the i-th unit. The effectiveness of the control structure is verified by the following scenario simulation:

[0093] Table 1 Station-level network control parameters

[0094]

[0095]

[0096] As shown in scenario 1: At 0.2s, P ref The power response of the PCC point of the station is shown in Figure 4(a) when the power drops from 1.0pu to 0.5pu instantly. It can be seen from the figure that under the station-level network control structure, the station can accurately track P ref changes.

[0097] As shown in scenario 2, the grid voltage phase suddenly changes by 0.1 rad at 0.2s, and the power response at the PCC point of the station is shown in Figure 4(b). It can be seen from the figure that under the station-level network control structure, the station can effectively respond to the phase mutation on the grid side.

[0098] As shown in scenario 3, the grid voltage amplitude suddenly changes to 0.9pu at 0.2s, and the voltage change at the station PCC point is shown in Figure 4(c). It can be seen from the figure that under the station-level network control structure, the station can maintain its voltage source characteristics when the grid-side voltage changes.

[0099] As shown in scenario 4: at 0.2s, the energy storage level of the lower energy storage power station changes, the power allocation ratio coefficients of units 1 and 3 are updated to 0.5 and 0.1, and the output power changes of each unit are shown in Figure 4(d). It can be seen from the figure that each energy storage power station can change its active output according to the change of the power allocation ratio coefficient while maintaining the total output power unchanged.

[0100] Based on the above simulations, the control method proposed in the present invention can accurately reflect the response characteristics of the virtual synchronous machine of the grid-type control from the station level in various scenarios, and at the same time can allocate the power output of each power station according to its actual energy storage level, without the need to carry out grid-type transformation of the entire station.

[0101] The device embodiments described above are merely illustrative, wherein the units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the scheme of this embodiment. Ordinary technicians in this field can understand and implement it without paying creative labor.

[0102] Through the description of the above implementation methods, those skilled in the art can clearly understand that each implementation method can be implemented by means of software plus a necessary general hardware platform, and of course, it can also be implemented by hardware. Based on this understanding, the above technical solution is essentially or the part that contributes to the prior art can be embodied in the form of a software product, and the computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, a disk, an optical disk, etc., including a number of instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods described in each embodiment or some parts of the embodiments.

[0103] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A power control and distribution method for energy storage power stations based on site-level network control, characterized in that: include: S1: Constructing a station-level network control structure, which is divided into two layers, the upper layer is the station control center, and the lower layer is the energy storage station; S2: The station control center generates a total power reference command of the station PCC point by simulating the synchronous machine power angle swing equation; S3: According to the operating status of the energy storage station in the lower layer, the operating status of the energy storage station is judged. If the status is normal, the total power reference instruction is received, and the power reference is allocated to each energy storage power station according to the energy storage level. Otherwise, the energy storage station exits operation and the charging and discharging program of the energy storage station is started.

2. A method for controlling and allocating power of an energy storage power station based on site-level network control according to claim 1, characterized in that: In step S2, the method for generating the total power reference instruction includes: S21: inputting the PCC point aggregate power to the station control center, providing the PCC point voltage phase angle by simulating the rotor motion equation, and generating the control equation; S22: Based on the voltage phase angle, convert the voltage vector to a virtual synchronous d q In the coordinate system; S23: Based on the d q The steady-state circuit equation in the coordinate system is based on the virtual internal potential E on the d-axis v The difference between the voltage at the grid-side converter terminal in the virtual synchronous coordinate system and the voltage at the grid-side converter terminal in the virtual synchronous coordinate system is divided by the set virtual impedance X eq , get the output current reference value of the station; S24: Using an instantaneous power equation to convert the current reference value into the total power reference instruction.

3. A method for controlling and allocating power of an energy storage power station based on site-level network control according to claim 2, characterized in that: In step S21, the control equation is expressed as: Where P ref，total is the total active power reference of the station, P sum is the total active power collected by the station at the grid connection point, ω p ,θ p are the speed and phase angle of the virtual synchronous coordinate system, ω0 is the rated speed, J and D are the virtual moment of inertia and damping, and t is the rotation time.

4. A method for controlling and allocating power of an energy storage power station based on site-level network control according to claim 2, characterized in that: In step S23, the virtual internal potential E v The control equation is: Among them, K v is the voltage droop control coefficient, E0 and U pref are the virtual internal potential and terminal voltage amplitude reference values, U p is the terminal voltage amplitude, T r is the voltage detection delay, and s is the differential operator.

5. The method for power control and distribution of energy storage power stations based on site-level network control according to claim 2 is characterized in that: In step S24, the calculation equation of the total power reference instruction is expressed as: Where P ref，pcc and Q ref，pcc are the power reference instructions of the PCC point of the station, is the voltage component of the station PCC point under the d-axis, It is the output current reference value of the station under the d-axis.

6. The method for power control and distribution of energy storage power stations based on site-level network control according to claim 1 is characterized in that: In step S3, define SOC i is the current energy storage level of the i-th energy storage power station. The steps of judging the operating status of the energy storage station include: S31: Divide the working state of the energy storage station into three ranges according to the current energy storage level, namely, emergency discharge mode, normal operation mode, and emergency charging mode, and define SOC max and SOC min The upper and lower limits of the energy storage power station operating in a normal operating mode; S32: When SOC min <SOC i <SOC max When SOC i >SOC max or SOC i <SOC min When the energy storage power station is shut down, the charging and discharging procedures of the energy storage power station are started.

7. A method for controlling and allocating power of an energy storage power station based on site-level network control according to claim 6, characterized in that: In step S32, the method for allocating a power reference to each of the energy storage power stations includes: uploading the energy storage level data of each unit to the station control center at a preset time period, synchronously updating the power allocation ratio coefficient of the energy storage power station, and then allocating the total power reference instruction to each unit.

8. A method for controlling and allocating power of an energy storage power station based on site-level network control according to claim 7, characterized in that: In step S32, the specific distribution method of distributing the total power reference command to each unit is expressed as: P ref,i =k l P ref,pcc Q ref,i =k i Q ref,pcc Where P ref,i , Q ref,i is the total power reference command allocated to each unit, k i is the power allocation ratio coefficient of the i-th energy storage power station, and n is the total number of energy storage power stations operating within the normal range.

9. The method for power control and distribution of energy storage power stations based on site-level network control according to claim 1, characterized in that: In step S1, the energy storage station is controlled by a grid-following control method, which is to make the power output track the total power reference instruction through power-current dual-loop control, and cooperate with the phase-locked loop to maintain phase synchronization with the PCC point.

10. A power control and distribution system for energy storage power stations based on site-level networking control, which adopts a power control and distribution method for energy storage power stations based on site-level networking control as claimed in any one of claims 1 to 9, characterized in that: The dispensing system comprises: A virtual synchronization module; inputting the PCC point aggregate power to the station control center, providing the PCC point voltage phase angle by simulating the rotor motion equation, and generating the control equation; Coordinate transformation module: based on the voltage phase angle, the voltage vector is transformed into a virtual synchronous d q In the coordinate system; Current reference module: Based on the d q The steady-state circuit equation under the axis is based on the virtual internal potential E on the d axis. v The difference between the voltage at the grid-side converter terminal in the virtual synchronous coordinate system and the voltage at the grid-side converter terminal in the virtual synchronous coordinate system, divided by the set virtual impedance X eq , get the output current reference value of the station; A power reference calculation module: converts the current reference value into a total power reference instruction using an instantaneous power equation; Decision module: judge whether the operation status of the energy storage station is normal, if yes, the energy storage station receives the total power reference instruction; otherwise, exit the operation mode and start the charging and discharging program of the energy storage station; Power reference allocation module: The energy storage level data of each unit is uploaded to the station control center at a preset time period, the power allocation ratio coefficient of the energy storage power station is updated synchronously, and then the total power reference instruction is allocated to each unit.

Images